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This was the original base for the hard valve that was introduced in France in 1915 and in the UK was made as the R Type.
In the original pin layout given to the R Type and subsequently used for countless later designs: Pin one connected to the anode, pin two was for the grid and pins three and four were for the filament.
B4 Types | Variants |
B4 | Standard British four-pin base. Early types had metal shell and later types were moulded. Used on the majority of early low-power valves. |
B4-1 | B4 with un-plated brass shell. Used on early R-types. |
B4-2 | As B4-1 but with plated metal shell. Use: most early receiver valves. |
B4-3 | B4 with plated metal shell having central groove. Early Marconi-Osram types. |
B4-E | B4-2 base with shortened filament pins. Early Ediswan types. |
B4/N | -2 base with pair of scissors contacts connecting to bottom studs. Nelson three-filament types. |
B4/M | B4 with moulded base, usually Bakelite. On later low-power valves. |
B4/W | Moulded B4 base with side screw connecting to series filament resistor. Used on Cossor 'Wuncell' range. |
The pin-outs below refer to the data researched by Keith R Thrower OBE.
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